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Three core-shell structures were prepared with pyrrole, glucose, and tetraethyl orthosilicate (TEOS), respectively, encasing magnetic Fe3O4 microparticles, through three different "green" approaches without any toxic solvents. Pt nanoparticles (NPs) were immobilized onto these supports with NaBH4 as the reducing agent. The as-prepared catalysts were characterized thoroughly by TEM, VSM, XRD, FT-IR, ICP, and XPS. As expected, the shells remarkably affected the distribution of Pt NPs and catalytic activity. Pt NPs dispersed evenly on the surface of Fe3O4@PPy and Fe3O4@C, which were much better than Fe3O4@SiO2. Most attractively, the prepared catalysts exhibited better kinetics, higher activity and stability than Pt/Fe3O4 and Pt/C for selective oxidation of ethanol to acetic acid and glycerol to glyceric acid with molecular oxygen in water. Among them, the catalyst with a shell of polypyrrole (PPy) showed the best catalytic property, affording yields of 88% and 55%, respectively. Moreover, it could be recovered facilely from the reaction mixture and recycled four times without any significant loss in activity.

It is important to develop a highly active and stable transition‐metal catalyst with dual‐functional properties in the reversible transformations between various saturated and unsaturated N‐heterocycles. Herein, we prepared the cobalt nanoparticles (Co NPs) apically encapsulated by the N‐doped carbon nanotubes catalyst (Co@NCNTs) via a multiple pyrolysis of low‐cost dicyandiamide and cobalt (II) acetylacetonate. The catalyst shows excellent activity and recyclability towards the oxidative dehydrogenation (ODH) and the catalytic transfer hydrogenation (CTH) for various N‐heterocycles. The structure of outer N‐doped carbon nanotubes (NCNTs) can protect Co NPs from aggregation and leaching. Moreover, the encapsulated Co NPs and the NCNTs may generate a synergistic effect. Both of them facilitate the high performance. The poisoning tests with KSCN were to clarify the different active sites for ODH and CTH reactions: the Co NPs could modify the NCNTs through electrons redistribution, therefore the NCNTs could directly activate O2 in ODH. The encapsulated Co NPs is enhanced by the doped N atoms which is good for the H2 activation in CTH. What's more, the mechanisms of ODH and CTH reactions were also proposed. This work provides a facile and low‐cost method to design catalysts, which are dual‐functional, highly active and stable, for industrial applications. [ABSTRACT FROM AUTHOR]

CoPd bimetallic nanoparticles (NPs) were successfully encapsulated in bamboo-like N-doped mesoporous carbon (bNMC) via a facile one-pot method through combination of dissolving chelation and carbonization reactions. The morphology, structure and composition of CoPd-bNMC was verified by detailed characterization including SEM, TEM, EDX, XPS, XRD, N2 adsorption–desorption, VSM, and ICP. The as-prepared CoPd/bNMC showed excellent activity and selectivity for Suzuki coupling under mild and green condition. Though the Pd content of CoPd/bNMC was half of Pd/bNMC, the catalytic performance of CoPd/bNMC was almost the same with Pd/bNMC, which was caused by its special bimetallic alloy structure, high BET surface area and pore volume. Importantly, CoPd/bNMC with magnetic property can be separated using external magnetic field and reused for five consecutive runs in the reaction of Suzuki crossing without significant loss of activity. It was found the Pd content only showed slight loss (2.3 wt.%) after five reused reactions, which was because CoPd bimetallic NPs were inside the bamboo-like N-doped mesoporous carbon. [ABSTRACT FROM AUTHOR]

Catalysts with high atom utilization efficiency accompanied by improved reactivity and durability are highly desired. Metallic MoO2 with its small size easily agglomerates, making it difficult to use in water splitting to obtain hydrogen by electrolysis. Here, the nano‐Cu‐mediated multi‐site method is proposed to prepare ultrafine MoO2 nanoparticles (NPs) dispersed on poly(diallyldimethylammonium chloride)‐decorated reduced graphene oxide (denoted as MoO2/PDDA‐rGO). The introduction of Cu NPs increases the number of growth sites for MoO2 on the PDDA‐rGO and simultaneously promotes the growth rate of MoO2 on PDDA‐rGO. As a consequence, the resulting size of the MoO2 NPs is only 2 nm and these are evenly dispersed on PDDA‐rGO. Significantly, the optimized catalyst has a low onset potential of −42 mV versus reversible hydrogen electrode (RHE), a calculated Tafel slope of only 42 mV dec−1, and good cycling stability of more than 40 h. This favored hydrogen evolution reaction (HER) activity is caused by the synergistic effects of MoO2 and PDDA‐rGO, rapid charge transport, and sufficient exposed active sites of MoO2/PDDA‐rGO. Feeling fine: A nano‐Cu‐mediated multi‐site method is proposed to prepare ultrafine MoO2 nanoparticles (NPs) dispersed on poly(diallyldimethylammonium chloride)‐decorated reduced graphene oxide (MoO2/PDDA‐rGO). The optimized catalyst has an onset potential as low as −42 mV vs. RHE, a calculated Tafel slope of only 42 mV dec−1, and good cycling stability of more than 40 h. [ABSTRACT FROM AUTHOR]

Abstract: There is a vital need to explore highly efficient and stable non‐precious‐metal catalysts for the oxygen evolution reaction (OER) to reduce the overpotential and further improve the energy‐conversion efficiency. Herein, we report a unique and cost‐effective lyophilization and thermal treatment two‐step procedure to synthesize a high‐performance hybrid consisting of CoFe alloy nanoparticles embedded in N‐doped carbon nanosheets interspersed with carbon nanotubes (CoFe‐N‐CN/CNTs) hybrid. The lyophilization step during the catalyst preparation leads to a uniform dispersion of carbon‐like precursors and avoids the agglomeration of metal particles. In addition, the inserted CNTs and doped N in this hybrid provide a good electrical conductivity, an abundance of chemically active sites, good mass transport capability, and effective gas adsorption/release channels. All these lead to a high specific surface area of 240.67 m2 g−1, favorable stability, and remarkable OER activities with an overpotential of only 285 mV at a current density of 10 mA cm−2 and a Tafel slope of 51.09 mV dec−1 in 1.0  m KOH electrolyte, which is even superior to commercial IrO2 catalysts. The CoFe‐N‐CN/CNTs hybrid thus exhibits great potential as a highly efficient and earth‐abundant anode OER electrocatalyst. [ABSTRACT FROM AUTHOR]

Abstract: The photoelectrochemical (PEC) water‐splitting efficiency of a hematite‐based photoanode is still far from the theoretical value due to its poor surface reaction kinetics and high density of surface trapping states. To solve these drawbacks, a photoanode consisting of NiO nanoparticles anchored on a gradient phosphorus‐doped α‐Fe2O3 nanorod (NR) array (NiO/P‐α‐Fe2O3) was fabricated to achieve optimal light absorption and charge separation, as well as rapid surface reaction kinetics. Specifically, a photoanode with the NR array structure allowed a high mass‐transport rate to be achieved, while phosphorus doping effectively decreased the number of surface trapping sites and improved the electrical conductivity of α‐Fe2O3. Furthermore, the p–n junction that forms between NiO and P‐α‐Fe2O3 can further improve the PEC performance due to efficient hole extraction and the water oxidization catalytic activity of NiO. Consequently, the NiO/P‐α‐Fe2O3 NR photoanode produced a high photocurrent density of 2.08 mA cm−2 at 1.23 V versus a reversible hydrogen electrode and a 110 mV cathodic shift of the onset potential. This rational design of structure offers a new perspective in exploring high‐performance PEC photoanodes. [ABSTRACT FROM AUTHOR]

Cobalt-based nanomaterials are promising candidates as efficient, affordable, and sustainable alternative electrocatalysts for the oxygen evolution reaction (OER). However, the catalytic efficiency of traditional nanomaterials is still far below what is expected, because of their low stability in basic solutions and poor active site exposure yield. Here a unique hybrid nanomaterial comprising Co@Co3O4 core–shell nanoparticle (NP) encapsulated N-doped mesoporous carbon cages on reduced graphene oxide (denoted as Co@Co3O4@NMCC/rGO) is successfully synthesized via a carbonization and subsequent oxidation strategy of a graphene oxide (GO)-based metal–organic framework (MOF). Impressively, the special carbon cage structure is very important for not only leading to a large active surface area, enhanced mass/charge transport capability, and easy release of gas bubbles, but also preventing Co@Co3O4 NPs from aggregation and peeling off during prolonged electrochemical reactions. As a result, in alkaline media, the resulting hybrid materials catalyze the OER with a low onset potential of ∼1.50 V (vs. RHE) and an over-potential of only 340 mV to achieve a stable current density of 10 mA cm−2 for at least 25 h. In addition, metallic Co cores in Co@Co3O4 provide an alternative way for electron transport and accelerate the OER rate. [ABSTRACT FROM AUTHOR]

Solvent-dispersible magnetite nanoparticles (Fe3O4) end-functionalized with amino groups were successfully prepared by a facile one-pot template-free method to immobilize PdII and Pd0 using a metal adsorption and reduction procedure. They were characterized by TEM, XRD, XPS, FT-IR and VSM. Interestingly, the PdII catalyst exhibited better catalytic activity for carbonylative cross-coupling reactions than the Pd0 catalyst. According to the catalytic activities of a variety of arylboronic acids and aryl iodides catalyzed by two kinds of Pd catalysts, the proposed reaction mechanism of Suzuki carbonylative cross-coupling reactions using the Pd catalyst was also inferred. More importantly, agglomeration of Pd0 nanoparticles was obviously observed in the TEM images of the catalysts after reactions. Therefore, agglomeration of Pd0 nanoparticles should be considered as a significant reason for different catalytic activities of the reactions catalyzed by immobilized PdII and Pd0 catalysts. Furthermore, the PdII catalyst revealed high efficiency and stability during recycling stages. [ABSTRACT FROM AUTHOR]

A palladium-based catalyst supported on amine-functionalized magnetite nanoparticles was successfully prepared by a facile one-pot template-free method combined with a metal adsorption–reduction procedure. The catalyst was characterized by TEM, XRD, XPS, FT-IR and VSM. The catalyst afforded fast conversions for various aromatic nitro and unsaturated compounds, and with a turn-over frequency (TOF) of 83.33 h−1under a H2atmosphere in ethanol, even at room temperature. Furthermore, it was found that the catalyst showed a high activity for the Heck reaction, affording over a 93% yield in all the cases investigated. Interestingly, the novel catalyst could be recovered in a facile manner from the reaction mixture and recycled eight times without any significant loss in activity. [ABSTRACT FROM AUTHOR]

In this work, Ni modified Pd nanoparticles immobilized on hollow nitrogen doped carbon spheres were successfully prepared, denoted as Pd/Ni-N/C. The Pd/Ni-N/C showed a moderate catalytic activity for the catalytic reduction of 4-nitrophenol as a model reaction. When applied for the simehydrogenation of phenylacetylene, the Pd/Ni-N/C exhibited a much better catalytic performance than some other Pd-based catalysts. What’s more, the selectivity of styrene could be kept at high levels even when the reaction time was prolonged. The superior catalytic performance may be ascribed to the incorporation of Ni and N species, which were detailedly characterized and contrastively demonstrated. The contained N groups could disperse and stabilize the supported metal nanoparticles. The Pd/Ni-N/C displayed no obvious decrease of catalytic activity and selectivity in the recycling tests, indicating the potential for various industrial applications. [ABSTRACT FROM AUTHOR]

• Small Rh nanoparticles were anchored on phosphate-doped porous carbon. • The Rh/P-mC catalyst exhibits excellent performance for alkenes hydroformylation. • The reaction mechanism of hydroformylation of alkenes was detailed investigated. The hydroformylation of alkenes to prepare aldehydes using rhodium-based catalysts has been widely investigated, while homogeneous Rh catalysts always suffer from poor reusability. Herein, a promising solution was proposed to introduce phosphorous heteroatoms into a porous carbon support to fabricate a stable and efficient catalyst (Rh/P-mC). And the obtained Rh/P-mC had high hydroformylation activity under mild reaction conditions. The substrate expansion experiment using different alkene substrates and the catalyst cycling experiment demonstrated the universality and stability of this catalyst. The hydroformylation reaction mechanism was also proposed, and the effect of the interaction between phosphorus and rhodium on the hydroformylation reaction was verified. Thus, this work has great application prospects for the highly efficient catalytic hydroformylation of alkenes and provides an efficient method for the design of high-performance hydroformylation catalysts. [Display omitted] [ABSTRACT FROM AUTHOR]

A new palladium-based electrocatalyst (Pd/PDIL-MWCNTs) with ionic liquids molecules derived from 3,4,9,10-perylene tetracarboxylic acid (PDIL) noncovalently functionalized multi-walled carbon nanotubes (PDIL-MWCNTs) decorated with palladium nanoparticles is fabricated through a facile and surfactant-free synthetic technique. Due to the introduction of PDIL molecules, the Pd/PDIL-MWCNTs remarkably possesses smaller mean nanoparticles (NPs) size, better distribution of Pd NPs and larger electrochemical active surface area than the Pd NPs immobilized on the MWCNTs and the harsh acid treated MWCNTs (AO-MWCNTs). Furthermore, the Pd/PDIL-MWCNTs exhibits the enhanced electrocatalytic activity and improved stability for ethanol electrooxidation compared with Pd/MWCNTs and Pd/AO-MWCNTs, owing to the role of PDIL functional molecules. Additionally, a possible synergistic mechanism of PDIL-MWCNTs and Pd NPs for ethanol electrooxidation is also proposed on the basis of the previous literatures and the experimental results. The results indicate that the PDIL-MWCNTs is a promising support for electrocatalyst and the Pd/PDIL-MWCNTs catalyst may be a well candidate for direct ethanol alkaline fuel cells. [ABSTRACT FROM AUTHOR]

The development of new catalysts with high catalytic activity for the hydrodechlorination (HDC) of chlorophenols (CPs) in the industrial polluted water has recently triggered various research interests. In this study, a novel N-doped mesoporous carbon microspheres (N-MCM) was synthesized through a nanocasting route using the low-cost and widely available dicyandiamide as precursor and MCM-48 nanospheres as the hard template. The synthesized N-MCM material exhibited a large surface area of 120.8 m 2 g −1 , pore volume of 0.24 cm 3 g −1 , average pore size of 9.9 nm and rich N content of 27.2 wt%. The characterization results of FT-IR, Raman spectrum and XPS illustrated that N-MCM had graphitic-like structures consisted of carbon nitride heterocycles, as well as amino groups. When N-MCM was used as catalyst support, Pd nanoparticles could be well dispersed in the mesopores and on the surface of the N-MCM. And the Pd/N-MCM nanocatalyst showed excellent catalytic activity for the eco-friendly HDC of CPs under green conditions in 1 h. While interestingly, when the reaction time was continued, the HDC product phenol can be further hydrogenated to a much more useful product (cyclohexanone) with selectivity above 85%. [ABSTRACT FROM AUTHOR]

Highlights: [•] A novel preparation of three-component Pd/ionic liquids/graphene heterostructure has been constructed. [•] The Pd-based nano-catalysts have relatively low price and higher resistance to CO poisoning when compared with Pt-based catalysts. [•] The nano-catalysts represent high electrochemical surface area and enhanced electrocatalytic activity for DAFCs in alkaline media. [ABSTRACT FROM AUTHOR]

Abstract: A novel and high-performance palladium-based catalyst for Heck reaction was prepared easily by the co-precipitation method. The catalyst was characterized by transmission electron microscopy (TEM), X-ray powder diffraction (XRD), vibrating sample magnetometry (VSM), X-ray photoelectron spectroscopy (XPS) and atomic absorption spectrophotometry (AAS). The catalyst afforded a fast conversion of the 4-bromonitrobenzene to 4-nitrostilbene at a catalyst loading of 5mol%, and the efficiency of the catalyst remains unaltered even after 6 repeated cycles. The excellent catalytic performance of the Pd/Fe3O4 catalyst might be attributed to the enhanced synergistic effect between Pd nanoparticles and magnetite. [Copyright &y& Elsevier]

Abstract: In this work, molecular logic element modified multifunctional silica nanoparticles having high magnetization have been successfully prepared. These multifunctional nanoparticles were characterized by Fourier transform infrared spectroscopy (FT-IR), transmission electron microscopy (TEM), Elementary analysis, X-ray powder diffraction (XRD) and Vibrating sample magnetometer (VSM). The characterization datum indicated that the organic ligand was successfully grafted on the surface of the magnetic silica nanoparticles. The fluorescent changes of the hybrid material upon the addition of cations (H+, F− and their mixture) is utilized as an INHIBIT logic gate at the molecular level, using the fluorescence intensity signal as output. [Copyright &y& Elsevier]

Abstract: In this work, quinoline group modified multifunctional silica nanoparticles having high magnetization and excellent Zn2+ selectivity have been successfully prepared. These multifunctional nanoparticles were characterized by high resolution transmission electron microscopy (HRTEM), Fourier transform infrared spectroscopy (FT-IR), thermal gravimetric analysis (TGA), X-ray powder diffraction (XRD) and vibrating sample magnetometer (VSM). The characterization data indicated that the organic ligand was successfully grafted on the surface of the magnetic silica nanoparticles. The fluorescent properties of the nanosensor were characterized and employed to detect Zn2+ with excellent selectivity and sensitivity (0.1μM) toward Zn2+ over other cations even in trace amount. [Copyright &y& Elsevier]

Abstract: A magnetic composite of multiwalls carbon nanotubes (MWNTs) decorated with Cobalt nanoparticles was synthesized successfully by a simple chemical precipitation and deoxidization method. The composite was analyzed by X-ray diffraction (XRD) and transmission electron microscopy (TEM). The pattern of XRD indicated that MWNTs and Cobalt nanoparticles coexisted in the composite. The TEM images revealed that the Cobalt nanoparticles were distributed on the surface of the MWNTs, with the size ranging from 5 to 15 nm. The hysteresis loops of the decorated MWNTs were measured by a vibrating sample magnetometer (VSM), the ferromagnetic signature emerged with the saturated magnetization of 5.8 emu/g, and the coercive of 310 Oe. [Copyright &y& Elsevier]

• Mesoporous MoO 3 /SiO 2 NN were successfully self-assembled without any surfactant. • Conventional methods involving chemicals are replaced by surfactant-free air route. • MoO 3 /SiO 2 NN material displayed remarkable pore structure and excellent amphipathy. • Novel MoO 3 /SiO 2 catalyst owned excellent catalytic desulfurization performance. Recently, oxidative desulfurization (ODS) is favoured by researchers because it is based on mild conditions and does not consume hydrogen. However, the preparation process of catalyst for ODS was not green or costly, which limits its further industrial applications. In this study, a facile route has been explored to grow the mesoporous MoO 3 /SiO 2 nanosphere networks (MoO 3 /SiO 2 NN) using low-cost air without surfactants. Herein, the air not only served as the template to self-assemble and form the nanosphere network structure but acted as a mesopore-directing agent to make mesopores on the MoO 3 /SiO 2 nanosphere. Moreover, the recovered waste mother liquor was also successfully applied to prepare nanomaterials. Gratifyingly, the nanocomposites of MoO 3 /SiO 2 NN displayed remarkable pore structure, large specific surface area (201 m2 g−1) and excellent amphipathy (CA = 24.7° and 13.6° of water and n-octane, respectively) making it a promising catalyst for two-phase ODS reaction with H 2 O 2 as an oxidant. Meanwhile, the high TOF value (56.6 h−1) and outstanding durability were obtained under optimum conditions (Yield > 99 % at 70 °C and O/S = 8:1 for 1 h, 20 mg catalyst) and the products were detected by GC–MS and 1H NMR. Therefore, an environmentally benign self-assembly procedure can facilely prepare more types of mesoporous catalysts for large-scale industrial application. [ABSTRACT FROM AUTHOR]

A novel Pd(0) compound immobilized on the surface of hollow magnetic mesoporous spheres, with Fe3O4 nanoparticles embedded in the mesoporous shell is prepared. [ABSTRACT FROM AUTHOR]